Hints and Tips - Powdercoating

From: David Cochrane
Sent: 26 January 2000
To: british-cars-pre-war
Subject: Powder Coating

Dear Pre-Warriors,

Your opinion on the following would be appreciated (but please don't copy it all back to us!):

On Mon, 24 Jan 2000 Nigel Coulter wrote:

... the subject of powder coating arose and Reg Nice shared my concern over its effectiveness - especially with regard to WHEELS. He reckons powder coated wire wheels are downright unsafe! and was going to write to the VSCC about it. He says that especially round the spoke nipple ends the coating lifts and this a) causes the spokes to loosen and b) water can get in and rust where you can't see. Interestingly I have just finished working on a '31 Morris Minor for a bloke and one of the things he wanted was for me to sort the wheels. One was in very poor condition, nice and shiny but four broken spokes and one missing. I found that it had been powder coated and the paint simply flaked off the spokes. I have sent given it to MWS for rebuilding, sand blasting and enamelling. So beware. I guess, as you say it is a quick and easy way to achieve a good cosmetic finish but as Reg says anywhere like the chassis where you have fixing holes, they will invariably need to clean and ream them out to size. DON'T rely on powder coated wheels.

David Cochrane replied:

I have spoken to two companies up here in the Midlands about this powder-coating versus stove enamelling argument, and both say that the former is a far superior process. I rang one of the companies this morning, because I had seen them recommended (in the Lagonda Club newsletter) as offering either process; the man there said that powder-coating was 40 years more modern than stove enamelling and much better; I read him your bit about spokes and he said that it couldn't have been applied correctly. He says stove enamelling is more prone to crack than powder-coating, all other things being equal. They can do either process equally well, so have no axe to grind. I only deal with companies that offer shot-blasting as well as powder-coating so that the metal doesn't have time to corrode or get dirty in between processes. I only hope that the experts are right, as I have had all my wheels done! It certainly seems to be a very good finish; I have filed the powder- coating on the chassis in order to get a flat surface (eg to mount the steering-box) and it doesn't show any sign of wanting to flake off; just files away like plastic padding, only seems harder. You wrote "He says that especially round the spoke nipple ends the coating lifts and this causes the spokes to loosen ..." I can't see the logic behind this. If the wheel has been done properly, the spokes will be tight whether there is paint there or not. I suggest that he hasn't had the wheels rebuilt properly and/or hasn't had the powder-coating applied directly after correct cleaning/blasting.

Nigel replied:

I think the powder coating thing needs the experts to opine. My experience has been of things that must have been done some time ago and in the last two recent examples the paint has simply flaked off. This morning I rang Motor Wheel Services who are rebuilding the Morris wheel for me and asked them whether they had come across problems with powder coated wheels and they said only when the wheel had not been fully rebuilt, i.e. the assembled wheel with existing spokes had been shot (or sand?) blasted then treated and painted. the problem, they reckoned, was residual rust developing. So I don't know what to think.

Some questions therefore arise: Has the process changed over the years? Are there good and bad practitioners, and how can one tell? Is there an aging process, or does longevity just depend on the thoroughness of the preparation?


From: Ed Swain
Sent: 26 January 2000
To: British-Cars-Pre-War
Subject: powder coating

I have only experience not expertise to add

The Singer Junior wheels had been powder coated, and the finish does look good without signs of any problems. This had been done by a 'professional' but the wheels I am sure had not been rebuilt. The inside of the rims are impossible to clean well, and after some time were still emitting small amounts of blast powder and rust. The thickness of coating, and slight variation in thickness did cause me a problem with the wheel fixing. By fettling and generally fiddling about I got the wheels to bed down onto the drum evenly, thereby eliminating the majority of wheel wobble. I have gone mad and painted the chassis, and I thought about powder coating. I decided against it because the additional bolted side members etc would be much more difficult to bed down, and assemble due to the thickness of the coat, and impossible to cover adequately when assembled. So I primed, undercoated, assembled, more undercoat and top coat. It made me feel better. On balance I would not go to powder coating particularly as all of my cars receive paint for protection as opposed to glamour.

Dr Ed Swain
Engineering Design Institute
Department of Mechanical Engineering
Loughborough University


From: Maggie Shapland
Sent: 26 January 2000
To: British-Cars-Pre-War
Subject: Re: powder coating

I too have experience of powder coating but not expertise. The Talbot wheels (artillery) were done probably 1975- the wheel centres became very thin but I managed to get some more wheels- which were also powdered but have been no problem. I cannot say that it was the coating process of the original wheels that made them so thin.

The Lanchester wheels (solid disc) were also done mid 70's and they are so solid and heavy (I need a tube to lift them onto the studs) I didnt believe I could ever have problems. However when I drove to York in August this year to the Lanchester rally, I found that one of my rims was starting to collapse with a massive split in it. The inside of the rim was found to be very thin. I had to get someone to weld a new rim on to the wheel for me at great expense. Tapping on the rims showed only the faulty one to sound "hollow" so I guess the others are OK, but I was lucky not to get a blowout on my rear wheel- and I wasnt too happy driving home 240 miles with no spare wheel. Neither car has wheel wobble or any trouble with tubes not seating. All my other paint jobs have been done with wirebrush and paint pot so not so vicious.

The paint on the Lanchester wheels had rust showing through so I have repainted them by hand

----------------------
Maggie Shapland, Computing Service, University of Bristol
Web page: http://www.cse.bris.ac.uk/~ccmjs/
1925 Lanchester 21, 1925 Talbot 10/23, 1929 Peugeot 190S, 1986 Moss Monaco


From: Richard Feibusch
Sent: 26 January 2000
To: Ed Swain
cc: British-Cars-Pre-War
Subject: Re: powder coating

Listers,

I have been using powder coating for over 5 years now with only good results. As far as I understand it, it is a new process of painting that will eventually be the ONLY acceptable process in the future as it is non-poluting in any stage. That means alot to govt. folks out here in California.

I've done wheels, engine pieces (It also is heat resistant to a point) patio furniture and kitchen appliances with great results. My dark green garden table and chairs have never dulled, chipped or rusted, even after 4 years of hot sun and salt air. I have repainted the front wheels (Corvette) on my daily driver '69 Malibu convertible three times while the powder coated, wider aftermarket rear wheels still look like new (again, parked in the sun and salt air).

As for wire wheels, they should be trued and tuned and all weak spokes replaced before powder coating as, once done, they can't be retouched but all powder coating is, is a new way of painting. The heat required is less than 400 degrees so it shouldn't be a threat to the old metal as well.

The shop that I use in San Fernando, CA has a new BIG oven and recently someone had a complete Mini shell done as well as his doors and boot and bonnet lids! I understand that there is now even a "conductive" body filler so the process will work over new body repairs. Usually I'm accused of being an "old guy" who is adverse to technology but this stuff seems to be real good.

Rick Feibusch
Venice Beach, CA

PS: The hot tip here in Los Angeles (stolen from the hot rodders) is to check the wire wheels for straightness, take them apart, powder coat the rims and hubs either body colour or a contrasting colour (usually dark red, cream, or light silver/gray) and then put them back together with new stainless spokes and nipples and a replated knockoff. A bit pricey but very impressive. At this point the wheels remain adjustable and the cracking at the nipples stops being an issue.


From: John McEwen
Sent: 26 January 2000
To: David Cochrane
Subject: Re: Powder Coating

Hello David:

I've been a great advocate of powder coating for the past 10 years. I have restored a number of motorcycles and cars and have made extensive use of powder coating in the preparation of frames and related pieces on mcs and under-the-hood(bonnet) items on cars.

Black powder coat cannot be beaten for durability and appearance in replacing stove enamelling for such parts. I have had the wire wheels on my MGB coated and after 5 years of use and many thousand miles am completely satisfied. The appearance has not deteriorated, wheels have remained true and clean up is much simpler than before. In fact, this is an obseration about coated engine and underhood parts - they stay cleaner and clean more easily.

John McEwen


From: John McEwen
Sent: 26 January 2000
To: Ed Swain
Subject: Re: powder coating

Ed, the only real difference between paint and powder coat is that the powder coat is superior. There are many different types of powder coat just as there are paints. Buy the coating you need for the job at hand. Powder coat is not used for glamour but for durability and superior resistance to abrasion and corrosion. It is an entirely satisfactory product. If you found that it was too thick and the wheels were bleeding blasting media your work was done improperly. You need to find a more experienced or patient applicator.

John McEwen


From: Barry Lovelock
Sent: 26 January 2000
To: David Cochrane
cc: british-cars-pre-war
Subject: Re: Powder Coating

Here's my twopennyworth:-

I have had about 15 Austin Seven wheels coated and they all look super, but and it is quite a big BUT, I will not have any more done. Reg Nice's comments are interesting, but I tend to believe the answer about the coating being poorly applied and I might add the wheels need to be perfect anyway. I always weigh mine - it may seem silly, but on average a well corroded one can be a pound or more lighter, allowing for spoke thickness differences etc. Some wheels fall apart when blasted, even if you think they won't.

Now to the BUT. You must check for spoke tightness and trueness of running before powder coating, because you can't adjust afterwards. However the real reason for me not to have any more done is simply that the Austin wheel locates positively on the rear hub and the thickness of coating will prevent this or when on it will not come off! I also believe the variation in thickness of coating causes difficulty in tyre fitting sometimes, I don't seem to have this problem with my enamelled or hand sprayed wheels. I know you will say this means the powder is applied too thickly, but it has occurred with two different companies.

The final reason is that the finished article really is too good, they were surely never like that in the period. Too many cars look too perfect. Mine are covered in oil - the engines anyway, thrashed within an inch of their lives, quite often very dirty, driven through deep fords (Sunday - wet feet!), just the way it should be and the way the VSCC likes it!

Barry Lovelock.


From: Richard Feibusch
Sent: 26 January 2000
To: JustBrits
cc: british-cars-pre-war
Subject: Re: powder coating

Ed,

Powder coating is an electrostatic process, paint charged neg, metal charged pos. then spray in the general direction of the part and the powder will stick everywhere but where it is masked. ALL OVER! The charge is left on the metal rack that holds the part so the powder will stay stuck. The whole thing is rolled into a big oven and slowly brought up to about 400 degrees, the powder melts and flows together into a glassy smooth finish. When it cools hard, it is hard to remove the coating without sandblasting it down to bare metal again. You can bang two pieces together and they will not chip - amazing. They now have flat and semi gloss colors as well as a primer (two steps: prime, let cool, then color, let cool) But things can get too thick for precision fit at this point, but remember, you can mask off areas thet might be affected by this.

Cheers,

Rick Feibusch


From: Chris Holbrook
Sent: 27 January 2000
To: british-cars-pre-war
Subject: Re: powder coating

I'm thinking about whether to use powder coating on the nether parts of a box saloon (A7), so this correspondence is interesting. As I understand it, Powder Coating is a process by which a fusible material is applied electrostatically and then encouraged to bond with itself and the substrate by cooking. Like paint, the PC material comes in a variety of formulas (polyester, epoxy), finishes and colours, and I would guess that some are appropriate to the kind of long-term exposure which chassis and wheels provide and others, less so. From my (non-automotive) experience of PC I would doubt whether it was suitable for a substrate which flexed, so would not trust it on spoked wheels or riveted/bolted chassis components. Maybe we used the wrong sort of PC!

Does anyone have any views on greasing/oiling the chassis rather than or as well as painting it? Most of it is hidden so the cosmetic disadvantage is not very significant.

Chris
Happiness is ....a well-oiled chassis?


From: Andy
Sent: 27 January 2000
To: Chris Holbrook
Subject: RE: powder coating

Chris wrote:
>Does anyone have any views on greasing/oiling the chassis rather than or as
>well as painting it? Most of it is hidden so the cosmetic disadvantage is
>not very significant.

A few years ago I cleaned all the oil and grease off the underneath of my Ruby saloon, wire brushed off all the rust and gave it all two coats of Finnigans primer followed by two coats of black gloss. It looked great, especially when it went on the ramp for its next MOT. It's starting to get a bit dirty now, so I might do it again sometime.

--
Andy

Andy's Austin Seven Page http://WWW.GEOCITIES.COM/MotorCity/4752/


From: David Cochrane
Sent: 27 January 2000
To: Rick Feibusch
Subject: Re: powder coating

Rick,
> ... They now have flat and semi gloss colors as well as a primer (two
> steps: prime, let cool, then color, let cool)...
> The shop that I use in San Fernando, CA has a new BIG oven and
> recently someone had a complete Mini shell done as well as his
> doors and boot and bonnet lids!

Does this mean that you can get the process good enough for body parts? I didn't think the finish I got was that good, fine for wheels & chassis etc but not for wings.

Regards,

David (Powder-coated A7 Special?)


From: Mike Lunch
Sent: 27 January 2000
To: Chris Holbrook
Subject: RE: powder coating

Chris on my A7 chummy I chose the "bead blast, zinc dipped and then Hammerite hand painted" route on the grounds that the hammerite is dead easy to touch up and apply in stages as and when needed, the Zinc dip should provide more corrosion protection that will ever be needed. Before mounting the body I put in a layer of chassis felt soaked in Waxoil.

Mike


From: Dr G W Owen
Sent: 27 January 2000
To: Chris Holbrook
Subject: Re: powder coating

Here is my two penny worth on the subject.

I am a great fan of powder coat and have usd it far more extensively than anyone else on this list seems to have suggested is possible.

On my JAP engined special, I was fed up with the paint falling off the ali bodywork due to all the abuse it got, so I powder coated the whole body. Now 10 years, countless events and sets of sticky numbers, teh body is tired and scared, BUT the powder hasn't chipped off anywhere. Did you know you can T Cut it? I also have had wheels done and have experienced some of the rusting problems, but only on very corroded wheels before they were powder coated

When I started to build the aero-engined special, I made a policyy decision at eh start to paint nothing. So I built the vast majority of the car, took it to bits, sent it off to my local powder coater (VSCC man Mike Sythes) and then picked it all up 3 days later. When I finished the body I did the same again and had the whole body done. I am very pleased I did it and the results have been great. The only snag is that the red I wanted for the body is not stable in ultra violet light (Mike warned me of this) and now 4 years later the colour on the tail is starting to fade.

BUT and this is the big but. The layer of powder coating makes the most excellent undercoat for body panels which are then to be sprayed, so when I get bored of the slightly faded look, a quick blow of with some 2 pack will allow me to join the polishers!!!!!

Geraint

Dr Geraint Owen
Department of Mechanical Engineering
University of Bath


From: John McEwen
Sent: 27 January 2000
To: british-cars-pre-war
Subject: Re: powder coating

Chris:

PC is more flexible than paint and far more durable. Some types of PC are more suitable for what you intend than others. There are different PCs for interior and exterior use. I believe that you want a polyurethane. Remember that PC adherence is based on blasting the surface to clean it so that complete adhesion can take place. PC is considerably tougher than paint and more able to withstand abrasion from road grit.

Finally, you need to keep in mind that the parts you want coated cannot be larger than the oven used by the applicator.

Powder coating is a superior protection to paint and oil-coating. It is far more able to withstand flexing and abrasion than almost any other surface protectant. It is not used simply for cosmetics. The final advantage is that PC surfaces are much more resistant to oil and dirt and are much easier to clean than traditional finishes.

John McEwen


From: Richard Feibusch
Sent: 27 January 2000
To: David Cochrane
Subject: Re: powder coating

Good point David - Yes and no - It usually leaves a mild "orange peel" that can't be properly rubbed out - It depends on how evenly it is applied and how well and evenly it is heated. It came out OK on the Mini but it isn't really for show but would cut down on the stone chips on a ralley car. I did parts like the bumper brackets and wheels on my Morris, as well as some engine pieces and just love the stuff - The Eastwood Co here in the states has developed a "Home Brew" powder coating kit that is limited only by the size of the oven section of your cooker!

Cheers,

Rick


From: Mike Rambour
Sent: 27 January 2000
To: british-cars-pre-war
Subject: Re: powder coating

Speaking of Powder Coating and its different types, does anyone know what the EastWood kit is ?

I purchased it a few months ago when I was getting dizzy from painting all the small parts on my Singer and it is really nice. No fumes, quick and easy. I got it with the expensive infrared lamp so I can do bigger parts and bought a toaster oven at the salvation army. I would not get the lamp now that I know better, yes it does big parts and yes I did my front axle and rear axle housing but it took forever, next time I will send those out to get done. Small parts are a dream though.

I have had to glassbead the stuff off when I did a boo-boo and it is on there really tough, its great stuff. Brake fluid does not seem to affect it but I didn't let it soak in brake fluid either. I was told that the epoxy powder coating is brake fluid proof and that the poly powder will be eaten by brake fluid after a short while. Yes, I am doing all my backing plates and wheel/suspension/etc parts this weekend and I guess it does not matter too much since I will use the EastWood stuff but I was just wondering. I didn't get this powder coating for its toughness, I got it because I already have some respiratory problems and this no fumes painting is the only way to go.

And never fear ! this will not be a over-restored car, it will be what I call "protected" from future corrosion. Some parts that were not originally painted will be powder coated and the entire car will be done by ME so I can safely guarantee it will not win any concours but it sure will drive GREAT and I will have FUN !

mike


From: Mark W Roper
Sent: 28 January 2000
To: British-Cars-Pre-War
Subject: Fwd: Powder Coating

I think Reg is talking out of his hat.
I have a 7 with powder coated wheels and in the past I have coated motor cycle wheels and they have been fine.
I have worked for a company that installed a powder coating plant, and if you had a piece of mild steel strip coated you were able to bend it back and forth until the steel fractured and the coating would not come off. I think a lot of people get confused with plastic coating which does come off, but if your wheels are prepared properly, ie shot blasted and FULLY degreased the coating will not come off. If however your wheels had loose spokes to start with powder coating will not fix them, but it would stop them loosening off any more.

Mark Roper
ps I don't work for any powder coating company, and I have spray painting facilities at home, but I will still rather have wheels coated.


From: Mark W Roper
Sent: 28 January 2000
To: Dr G W Owen
Subject: Re: powder coating

You can have a uv stable clear coat over any colour

Mark


From: Dr G W Owen
Sent: 28 January 2000
cc: british-cars-pre-war
Subject: Re: powder coating

One thing you might like to know about powder coating is that while it is tolerant of petrol and brake fluid, IT IS SOFTENED BY LOCTITE (nutlock etc)

So be careful where you get drips off the bottle!

Geraint

Dr Geraint Owen
Department of Mechanical Engineering
University of Bath


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